exhaust brake compred to a Jake brake

[JACKRABBIT4106]

For those of you instred there is a set of used jakes on the E place.
Erik/Melissa
 4106
http://cgi.ebay.com/JAKE-BRAKE-FOR-DETROIT-DIESEL-6-8V71-6-8V92-N-R_W0QQitemZ130184547661QQihZ003QQcategoryZ50466QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[DrivingMissLazy]

Richard,

If my Jakes kept everything "cool" and i could come down the grapevine grade, 8%, at 70mph....I would probably get in that far.  Would service brakes stop me at that speed on that grade in a 9?

Thanks,

John

John, since so many of the large vehicles coming down the grapevine do not have Jakes, then yes I feel certain that one stop, from 70 mph, with cold brakes would be no problem at all. I know that on my Eagle or 4104 it would have been a piece of cake. Perhaps Russ, with his many years of traversing the grapevine in a seated coach could elaborate on this.

Richard

[boogiethecat]

Manasst (and others)
Before you guys write off  the possibility of a Telma going into your bus, why don't you check it out a bit.  Their "focal" retarder series mounts right on to the rear end and eats 3.5" of driveshaft at most.  The Focal series was specifically designed for rear engine busses and vehicles with short drivelines.
 I know there's a lot of vehicles that won't accomodate a telma, but there's quite a few that will as I understand it from reading the Telma literature.  For example with  Rockwell R series axles, depending on the yoke you use you only need to shorten the driveline from between 1.4 to 3 inches with 180 series axles, or 3.3 to 3.5" for 160 series axles.
There may be hope...
Cheers
G

Ref:  http://www.telmausa.com/TELMATECHWEB/DOC/PDF/TIL05046%20DRIVE%20SHAFT%20SHORTENING%20MERITOR%20FOCAL.pdf
and
http://www.telmausa.com/TELMATECHWEB/tech.html

[JohnEd]

Richard,

Thank you for that reassurance.  I have always needed some small protection from myself and I have little doubt that i would be a heavy user of Jake, if I had it, and become dependent.  Service brakes as the "aux system" would be my concept.

Thanks again,

John

[RJ]

John, since so many of the large vehicles coming down the grapevine do not have Jakes, then yes I feel certain that one stop, from 70 mph, with cold brakes would be no problem at all. I know that on my Eagle or 4104 it would have been a piece of cake. Perhaps Russ, with his many years of traversing the grapevine in a seated coach could elaborate on this.

Richard

John & Richard -

IBME that a fully loaded Jake brake-equipped MC-9 (44 passengers and three full baggage bays) with either the 8V71/HT-754 or 6V92TA/HT-754 will hold 62 - 65 mph in high gear coming down off the 6% Grapevine on I-5 without having to touch the brakes or throttle.  MCI 102A3 with the 8V92 would actually slow down - had to feather the throttle some to maintain the 62-65 target speed.

Richard - the majority of 18-wheelers and coaches on the Grapevine today all have Jakes or equivalent.  (BTW, the 18-wheelers are restricted to 35 mph on this grade.  Buses are not.)

As for the Telmas, the 1977 "New Look" Flxible transits we had at the transit property had these installed on the front (input pinion side) of the V-drive Rockwell rear axles.  These were integrated into the service brake pedal - the harder you braked, the more the Telma would work.  Transit brakes are abused more than any other coach, and the Telmas doubled the lining life of the friction brakes.  I remember seeing one of these on the hoist in the shop one time, and thinking that the space was awfully tight around it.  Probably wouldn't fit on a GMC, where there's less space than a Flx.

Most coaches have sufficient brakes to completely stop the vehicle on a downhill grade a few times before going away totally due to fade.  The thing you have to remember is that your stopping distances are much, much greater on a downhill grade, due to gravity working against you, and especially with these heavy vehicles.  It's these longer stopping distances that kills the brakes with the heat build-up.

And JohnEd, if you want to come off the Grapevine at 70+ in your MC-9, that's your decision.  May not be a safe decision, but it's yours. 

FWIW & HTH. . .

 

[makemineatwostroke]

Boogiethecat, the reason Telmas are popular in Europe is because Jake never built brakes for the European truck engines.Their market has been Cat,Detroit,Cummins and Mack, it was in 2007 before they would build for the MBE4000 engine. they may build for others now but not in the past

[DrivingMissLazy]

Richard - the majority of 18-wheelers and coaches on the Grapevine today all have Jakes or equivalent.  (BTW, the 18-wheelers are restricted to 35 mph on this grade.  Buses are not.)

Thanks Russ.

30 years ago when I was doing most of my driving in that area, Jakes were not apparent on most of the vehicles and there were a few that were significantly exceeding the 35 mile speed. Definitely nor safe or recommended. That is very definitely a wicked downgrade.

Most coaches have sufficient brakes to completely stop the vehicle on a downhill grade a few times before going away totally due to fade.

I should have mentioned that I was only talking about coaches. I never had my 18 wheeler over the grapevine. I did miss a gear once coming down the Baker grade (toward LA) with a very big load of surplus gensets from the military surplus center in Utah. I was able, with not problem, to bring the rig to a stop however so that I could get it back into a suitable gear.

As Russ stated, I also believe the brakes on any large rig are capable of making two or three total stops on any large grade as long as they are not hot to start with and that they are in properly maintained condition.

Richard

Probably much more so than when I was driving one so many years ago. LOL

[JohnEd]

Russ,

I stand admonished and I deserve to be.  It is in my nature to push the limits...not bragging, just being honest.  I don't feel unique, totally, in that regard.  Actually, I am a lot more responsible than i sound.  I don't have an MCI 9 but when I do I am sure I will develop the appropriate caution.  You and yours are safe, honest.

My first comment here was that I had bad feelings about letting a jake lull me into a sense of security.  I have never stopped anything like a 9 from "speed" on a serious downgrade and I honestly didn't know if it could be done.  I remember in Pa. that missing a shift was a disaster for those guys and they sat in a very low gear all the way to the bottom.  As a kid I hear adults say that if a truck got going over a certain speed it couldn't be stopped.  That stuck in my mind all these years.   Guess it doesn't make all that much sense that so many truckers would all be that cavelier.

Thanks Russ,

John

[houndbus]

OK...now everyone will know how little I know about Jakes.  I have a 4106 without Jakes here in Cincinnati.  So far, only traveled within 200 mile radius of Cincy with no problems with braking.  However, the day is going to come then I want to cross Jellico mountain heading for Florida or someplace else with some really big grades  I understand the value and use of the engine for braking.  Having said all that, here are my questions:
1. What are jakes and how do they work?
2. Are they necessary?
3. If yes to question 2, when are they necessary?
4. If it is determined I need them, where would I get them and much would I expect to pay for them?
5. How would I install them?

I realize this is a tall order but appreciate input to any and all the above
Thank you 

[JohnEd]

Hound,

Yes you do.

There was a complete Jake sys including the high rise valve  covers  on ebay.  Make it a favorite search and start bidding.

I only know what they tell me.

John